Chapter 5 - Pharmacokinetics and Pharmacodynamics of Inhaled Drugs
This chapter includes following sub-chapters:
Chapter 5.1 - Inhaled Drug Classes
Nicholas Gross, MD, PhD, FRCP (Lond)
Inhalation is currently used as the preferred method of administering drugs for airway diseases such as asthma and chronic obstructive pulmonary disease (COPD). The principal such agents are beta2-adrenergic agents, antimuscarinic agents and corticosteroids. Antimicrobial agents are also used for well-circumscribed disorders such as cystic fibrosis and viral pneumonias. However, the advantages of administering agents by this route have led to its use for other agents such as nicotine and insulin. The inhalational route is being explored for other agents as an alternative to other means of delivering agents to the body.
Chapter 5.2 - The Pharmacokinetics of Inhaled Drugs
Glyn Taylor, BSc, PhD
The pharmacokinetic (PK) profile of a drug after inhalation may differ quite markedly from that seen after dosing by other routes of administration. Drugs may be administered to the lung to elicit a local action or as a portal for systemic delivery of the drug to its site of action elsewhere in the body. Some knowledge of PK is important for both locally- and systemically-acting drugs. For a systemically-acting drug, the plasma concentration-time profile shares some similarities with drug given by the oral or intravenous routes, since the plasma concentrations (after the distribution phase) will be in equilibrium with concentrations at the site of action. For a locally-acting drug, however, the plasma concentrations reflect its fate after it has been absorbed and removed from the airways, and not what is available to its site of action in the lung.
Chapter 5.3 - Inhalation Pharmacodynamics
Ronald K. Wolff, PhD
Pharmacodynamics (PD) is discussed in relation to inhalation exposure to inhaled pharmaceutical and toxic agents. Clearly PD is closely related to pharmacokinetics, and this relation is illustrated with reference to inhaled insulin. PD can be related to pharmacologic responses, and some examples are cited. However, PD can also be thought of as the improvement or deterioration in lung disease state. Some of the major PD endpoints, including histopathology, pulmonary function, and bronchoalveolar lavage are reviewed. Brief reference is also given to other specialty biomarkers of PD response.
